Aug. 6 (UPI) -- New fossils suggest hadrosaurs and therizinosaurs migrated between Central Asia and North America 100 million years ago.
The ancient dinosaur remains, dated to the Late Cretaceous, were recovered from the Cantwell Formation in Alaska's Denali National Park. The discovery marked the first time hadrosaur and therizinosaur bones have been found together in North America.
Hadrosaurs, known as duck-bill dinosaurs, were abundant in what is now Alaska, but therizinosaurs, unusual, long-necked herbivores, are most associated with Central Asia.
"Hadrosaurs are very common and found all over Denali National Park," Anthony Fiorillo, chief curator and vice president of research and collections at the Perot Museum of Nature and Science in Dallas, Texas, said in a news release. "Previously, they had not been found alongside therizinosaurs in Denali."
The duo have been found together in Asia, but never before in North America.
"In Mongolia, where therizinosaurs are best known -- though no footprints have been found in association -- skeletons of hadrosaurs and therizinosaurs have been found to co-occur from a single rock unit so this was a highly unusual find in Alaska, and it prompted my interest," Fiorillo said. "From our research, we've determined that this track association of therizinosaurs and hadrosaurs is currently the only one of its kind in North America."
In addition to studying the fossil co-occurrence, a team of sedimentologists, geologists, paleobotanists and paleoecologists characterized Alaska's habitat during the Late Cretaceous. Their findings -- published this month in the journal Nature Communications -- suggest parts of Denali offered wet, marsh-like environments, similar to the types of habitat where hadrosaurs and therizinosaurs congregated in Asia.
"This study helps support the idea that Alaska was the gateway for dinosaurs as they migrated between Asia and North America," said Yoshitsugu Kobayashi, researcher from Hokkaido University Museum.
The discovery could help scientists connect other species with similar habitat preferences.
"This discovery provides more evidence that Alaska was possibly the superhighway for dinosaurs between Asia and western North America 65 to 70 million years ago," said Fiorillo.